The present invention relates to the prevention of fraud and more particularly to the prevention of fraudulent misappropriation of credit/debit card authorization numbers and passwords when public pay phones are used.
A fraud scheme that has recently come to the attention of telecommunication service providers involves pay phones located in public areas such as airports, train stations and the like. Many such pay phones may not emit an audible ringing sound when a call incoming call is being attempted to the phone. For example, an owner of a restaurant having a pay phone installed as a convenience to the patrons may have the ringer of the phone disabled so that ringing of the phone, as is often caused by mis-dialed numbers, will not annoy others in the restaurant. Alternatively, the pay phone may be programmed that it may ring only once initially, so that incoming calls may be received by a party expecting a call but does not cause undue disturbance to others. Similar measures are often employed in larger public venues, such as airports, where a large number of pay phones are installed side by side and ringing of such phones would only cause confusion and disturbance.
Perpetrators of calling card fraud use this circumstance to obtain calling card numbers from unsuspecting callers. A fraud perpetrator will place a call to a payphone, which will not ring at all or will ring only once and then remain silent. An unsuspecting caller wishing to place a call using a calling card or credit card using the phone will lift the receiver of the phone without being aware that the phone is receiving an incoming call. Upon lifting the receiver, or in other words going xe2x80x9coff-hookxe2x80x9d, the caller will be connected to the fraud perpetrator rather than just to the central office of the telephone network. The fraud perpetrator may even provide a false dial tone sound to convince the caller that they are properly connected to the telephone central office. The caller then dials an access number, the digits of which are usually conveyed by audible in-band signaling tones and maybe easily received by the fraud perpetrator. As many calling card services utilize special sounds and verbal prompts to trigger the caller to input calling card number and personal identification number (PIN number), the fraud perpetrator may cleverly reproduce these sounds in proper order so that the caller cannot distinguish the fraudulent connection from a legitimate connection. Thus, the unsuspecting caller unwittingly provides the fraud perpetrator with calling card and PIN numbers through the telephone line. The fraud perpetrator may then simply disconnect the call, leaving the caller to believe that the call was perhaps mis-dialed or was simply unsuccessful. The caller then usually hangs up and tries again, often without suspicion that a fraud has occurred.
In a variation, the fraud perpetrator may even use two telephone lines so that the call may be completed through the intended service provider in a normal fashion as expected by the caller. The fraud perpetrator simply reoriginates the call along the second line, couples the two lines together, and records the DTMF tones sent. This practice further prevents the caller from being alerted to the fraud taking place. Even though the call is successful, the fraud perpetrator has obtained the caller""s private account information and may use the information to fraudulently incur substantial calling card charges or credit card charges before the caller becomes aware of the fraud.
A similar scheme is directed at telephones that use card readers. Oftentimes, a caller will xe2x80x9cswipexe2x80x9d a calling card or credit card through a magnetic card reader as a first action, even before checking for dial tone or before taking the phone on-hook and off-hook to ensure a legitimate connection to a telephone switching office. In this case, a fraud perpetrator may already be connected to the telephone and be able to record the data signals transmitted from the card reader.
Another scheme is possible wherein the receiver of a telephone is lifted from the cradle slightly so that the phone appears to be on-hook when it is actually off-hook and connected to a remote party. While this fraud technique works even if the ringer is enabled, it requires the perpetrator to occasionally approach the target telephone, either to redial the fraud connection or to answer the ringing phone and leave it propped off-hook. This method is less preferable to perpetrators because it increases the chances of being apprehended. Even so, this scheme is viable especially where pay phone owners are unwary. It is the caller or the service provider, rather than the pay phone owner, who is victimized. by the fraud and the losses may be substantial.
Accordingly, there is a need for a means of preventing these occurrences of calling card and credit card fraud.
To prevent the type of credit/calling card abuse outlined above, a pay phone of the present invention may be provided with a device that disables the keypad under certain circumstances. In one to exemplary embodiment, a means is provided for monitoring incoming, or in-bound, calls from the fraud perpetrators that might be answered by an unsuspecting caller wishing to place a call. If the telephone receiver is lifted while an inbound call is detected, the device disables the data transmitting means of the telephone, such as a keypad or a card reader. This prevents the caller from inadvertently sending data to a fraud perpetrator. Especially with the keypad being disabled, the caller will not hear the expected dialing tones as they attempt to enter data using the keypad. Naturally, the caller will tend to momentarily depress the xe2x80x9chookxe2x80x9d on the phone, thereby disconnecting the incoming call from the fraud perpetrator. This action ensures connection to the telephone central office and subsequent input from the caller will reach a legitimate service provider as intended. In accordance with an exemplary embodiment of the present invention, this action also restores the normal function of the keypad or card reader so that the caller may subsequently use the phone in a normal manner.
In accordance with a first exemplary embodiment, a circuit added to the pay phone circuitry is designed to monitor for any incoming call signals, for example, by way of detecting the incoming ringing current. The circuit also monitors when the handset of the pay phone is lifted off-hook. If it is determined that the handset of the payphone has been lifted while a incoming call was present, then the circuit will disable the generation of DTMF (dual tone multi-frequency) signals by the telephone so that keypad input from the caller at the pay phone will not be transmitted over the telephone line. The DTMF generation is again enabled only after the caller subsequently places the telephone back on-hook. By this manner of operation, the caller may use the phone in the usual fashion to enter calling card number and PIN number to a legitimate service provider but is prevented from unwittingly providing such information to a fraud perpetrator.
A second exemplary embodiment of the instant invention further provides a circuit for discriminating the tones on the telephone line to detect the presence of a legitimate dial tone, such as the combination of precise 350 Hz and 440 Hz tones normally provided by a local telephone company or a private branch exchange switch. This aspect makes it more difficult for a perpetrator to use primitive equipment, such as a tape recorder or an electronic oscillator, to mimic dial tones. Most callers do not have the ability to discern an authentic dial tone from a false one. With the detection of a true dial tone when the handset is lifted off-hook, a clear line to the intended telephone exchange is further ensured.
Given that the circuits required can be easily added to the conventional telephone circuitry and are relatively inexpensive, the present invention is able to economically prevent the type of fraud described above.